The present invention generally relates to wind turbines having a machine nacelle and a rotor including at least one rotor blade and a hub. The present invention specifically relates to rotor blade bearings which are provided for rotating the at least one rotor blade about its longitudinal axis such that a pitch angle of the respective rotor blade may be adjusted.
Wind turbines are used as an efficient conversion means to convert environmental energy into electrical energy. The rotor of a wind turbine has a main shaft and drives an electrical generator which converts the mechanical rotational energy into electrical energy. The conversion of environmental energy in the form of wind energy into mechanical rotational energy is provided by means of the at least one rotor blade which typically is shaped as an airfoil.
The pitch angle of the rotor blade may be adjusted in order to cope with varying wind velocities such that a driving moment applied at a main shaft of the wind turbine may be adapted to changing environmental conditions of the wind turbine.
The pitch angle of an individual airfoil (rotor blade) may be adjusted, i.e. a rotational position of the individual rotor blade with respect to its longitudinal axis may be adjusted. Typically, each rotor blade of a wind turbine is connected to the hub of the wind turbine via a rotor blade bearing.
As rotor blades are large and heavy components mounting of an individual rotor blade at the hub of a wind turbine is a major issue. The rotor blade bearing is connected to the hub of the wind turbine by means of a plurality of bolt-screw nut pairs which are typically fastened and tightened in a predetermined order.
A large number of bolt-screw nut pairs provides a secure connection of the individual rotor blade bearing to the hub. On the other hand, fastening and tightening of a large number of screw nuts onto bolts is a time-consuming and costly measure.